Up to 10% of adults will develop a thyroid nodule in their lifetime. Although the majority of these are benign, more than 12,000 new cases of thyroid cancer develop each year in the United States. The diagnostic tools available to discriminate benign from malignant neoplasms are not reliable, which results in a large number of unnecessary surgeries. Furthermore, prognostic markers are not particularly useful. A better understanding of the biology of these frequently occurring endocrine neoplasms is needed to address these clinical shortcomings.